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Biomedical subjects

Y Gu

Publications and source records attributed to Y Gu.

At least 145 records · Page 8Linked to original sources
PubMed2000

Modulatory effects of the nucleus of the basal optic root on rotundal neurons in pigeons.

The present paper reports for the first time in birds the modulatory effects of the nucleus of the basal optic root (nBOR) on visual neurons in the nucleus rotundus in particular and those of the accessory optic system on the tectofugal pathway in general. Pharmacological blockade of the nBOR by lidocaine led to a decrease or increase in visual responsiveness of rotundal cells, suggesting excitatory or inhibitory actions of the nBOR on rotundal cells. These results were confirmed by changes in the excitability of rotundal cells following electrical stimulation of the nBOR. Response latency measurements implied that there might be at least two pathways from the nBOR to the nucleus rotundus, one being a direct excitatory pathway and the other an indirect inhibitory pathway possibly mediated by the subpretectal nucleus and the interstitio-pretecto-subpretectal nucleus, which have been thought to send inhibitory afferents to the nucleus rotundus. Taken together with previous neuroanatomical and immunocytochemical studies, it is suggested that modulatory interactions might exist between the nBOR and the nRt in particular and between the accessory optic system and the tectofugal pathway in general in birds.

Animals↗
PubMed2000

CTLA4Ig inhibits T cell-dependent B-cell maturation in murine systemic lupus erythematosus.

Long-term administration of CTLA4Ig prevents the onset of disease in systemic lupus erythematosus-prone (SLE-prone) NZB/NZW F1 mice. To determine the mechanism of this effect, we engineered an adenovirus that expresses murine CTLA4Ig. Administration of a single high dose of this virus results in long-term expression of CTLA4Ig in the serum and absence of an immune response to the adenoviral vector. We administered Ad-CTLA4Ig to 19- to 22-week-old NZB/NZW F1 mice and evaluated the effect on anti-DNA antibody-producing B cells. We show that CTLA4Ig has a beneficial effect on murine SLE for as long as it is present in the serum. This effect is associated with decreased expansion of both the IgM and IgG autoreactive B-cell population, inhibition of immunoglobulin class switching, decreased frequency and altered pattern of somatic mutation, and a marked decrease in the numbers of activated CD4-positive T cells. In contrast, intrinsic B-cell hyperreactivity and the survival of plasma cells in the bone marrow, both of which are less dependent on T-cell help, appear to be unaffected by CTLA4Ig. High-dose CTLA4Ig did not induce permanent tolerance in this autoimmune disease model. Furthermore, although the mice survived in a conventional housing facility, treatment with Ad-CTLA4Ig was immunosuppressive.

Abatacept↗
PubMed2000

Moiré technique for spatial coherence measurements of soft-x-ray lasers.

We present a novel moiré diagnostic that allows the time-averaged spatial coherence properties of soft-x-ray lasers to be measured. The technique is an extension of the theoretical work in a recent paper [J. Opt. Soc. Am. A 16, 323 (1999)] and is based on the concept of decompositions of the far-field divergence for partially coherent beams. An appealing feature of the approach is that the spatial coherence width at other planes can be evaluated from the measured one at a given plane on the assumption of shape-invariant beams.

Computer Simulation↗
PubMed2000

Treatment effects of simple fixed appliance and reverse headgear in correction of anterior crossbites.

The aim of this study was to compare the skeletal and dental changes contributing to the correction of Class III malocclusion using a 2 x 4 appliance and reverse headgear in the mixed dentition. Seventeen consecutive patients (mean age, 9.7 years) with pseudo-Class III malocclusions and an anterior functional shift and straight or concave facial profile were treated with a simple fixed appliance. Another 20 consecutive patients (mean age, 8.5 years) with Class III incisor relationship and straight or concave facial profiles, were treated with reverse headgear. Lateral cephalometric films taken at the beginning of treatment, the end of the treatment, and 1 year after the active treatment, were analyzed with the modified Pancherz analysis. After active treatment, the overjet correction, 5.2 mm and 6.5 mm on average, respectively, were achieved using the 2 x 4 and reverse headgear. The overjet correction by the 2 x 4 appliance was due to dental changes only. In the reverse headgear group, 60% of the overjet correction was due to dental changes and 40% due to skeletal changes. During the 12 months follow-up period, the overjet was unchanged in the 2 x 4 group (1.6 mm) and decreased in the reverse headgear group, the difference being statistically significant (P <.05). The change of jaw relationship was similar between the 2 x 4 and reverse headgear groups. During the follow-up period, a decrease in overjet in the reverse headgear group was mainly due to forward growth of the mandible and proclination of lower incisors. The overjet in the 2 x 4 group was unchanged due to dental compensation (1.6 mm). To conclude there was a similar amount of overjet correction in the 2 x 4 and reverse headgear groups. Overjet correction by the simple fixed appliance was produced by dental changes whereas in the reverse headgear group, it was produced by both dental and skeletal changes.

Cephalometry↗
PubMed2000

Effect of sulfated colominic acid on enteric virus (rotavirus, poliovirus and coxsackievirus) infections in vitro.

Sulfated colominic acid exhibited suppressive effects on SA11 (simian rotavirus)- and MO (human rotavirus)-infections, but not on Wa (human rotavirus)-, Sabin 1 (poliovirus 1)-, and Nancy (coxsackie B3 virus)-infections, in vitro. The infection of SA11 was found to be inhibited by mixed treatment and early posttreatment with sulfated colominic acid, but not by pretreatment, by plaque assay and multiple growth assay. The results were confirmed by the infectivity titer, RNA polyacrylamide gel electrophoresis, and electron microscopic analysis. The mechanism of the suppressive effect was suggested to be adsorption inhibition at an early stage of the infection.

Cells, Cultured↗
PubMed2000

The role of cyclosporine A and interleukin-2 in obliterative airway disease in a rat tracheal transplant model.

The pathogenesis of obliterative bronchiolitis (OB) following lung and heart-lung transplantation remains unclear. We evaluated the role of CsA and IL-2 on the development of obliterative airway disease (OAD) by administrating exogenous IL-2 in a CsA-treated rat tracheal transplant model. Tracheal grafts were implanted into the peritoneal cavity from Brown Norway (BN) to BN rats or to Lewis (LEW) rats. Allotransplant: No treatment was given in group 1. Short-term CsA (25 mg/kg, i.m. on POD 2 and 3) was used in group 2. Group 3 was treated with long-term CsA (25 mg/kg, i.m. on POD 2 and 3, followed by 5 mg/kg on POD 4 to 27). Administration of IL-2 (300, 000 IU/kg, i.p. on POD 15 to 19 and 22 to 26) was performed to long-term CsA treated rats in group 4. Isotransplant: No treatment was given to group 5, group 6 was treated with IL-2 (same regimen as in group 4). Grafts were harvested at different time points after Tx for histological assessment. No luminal obliteration was observed in group 5 and 6. Complete luminal obliteration was noted 4 weeks after Tx in group 1. In group 2 and 3, obliterative lesion occurred 4-6 weeks after CsA withdrawal. IL-2 increased epithelial loss, lymphocytic infiltration, and obliterative changes in group 4. Our results suggest that OAD is an immune mediated disorder. Furthermore, administration of exogenous IL-2 might be able to abrogate the protection from OAD by CsA therapy.

Animals↗
PubMed2000

[Effects of hypoxia on expression and activity of matrix metalloproteinase-2 in hepatic stellate cell].

OBJECTIVE: To study the effect of hypoxia on the expression and activity of matrix metalloproteinase-2 (MMP-2) in the hepatic stellate cell (HSC). METHODS: The expression of MMP-2 and tissue inhibitor of metalloproteinase-2 (TIMP-2) in cultured rat HSC was detected by immunocytochemistry (ICC). The relative amount of MMP-2 and TIMP-2 in the culture supernatant was assayed by ELISA and the activity of MMP-2 in supernatant was examined by zymography. RESULTS: The expression of MMP-2 was enhanced in hypoxia group as compared with that in control one (t' 3.4685, P<0.05 ), while the expression of TIMP-2 was decreased (t'=2.5673, P<0.05). The activity of MMP-2 was lower in hypoxia group than in control one (t'=4.270, P<0.01). Comparing the varied duration of hypoxia, the relative amount of MMP-2 protein was the highest in 6 h group (6h vs 12h, t=4. 0945, P<0.001; 6h vs 24h, t=2.4652, P<0.025), with a contrary curve in TIMP-2. CONCLUSION: Hypoxia promotes the expression of MMP-2 and inhibits the expression of TIMP-2 in HSC. It is more notable at early stage of hypoxia.

Animals↗
PubMed2000

[Study of the radioprotective effects of TMG on teratogenic malformations in irradiated mice].

ICR mice fetuses in the organogenesis stage were used to clarify experimentally the mechanism of the protective effect of vitamin E derivant (TMG: 2-(alpha-D-Glucopyranosyl) methyl-2, -5, -7, -8-Teramethylchorman-6-working woman) on the effects of radiation. The authors paid careful attention to radiation, and the radioprotective effects of TMG on the induction of malformations was examined. Radiation is an important consideration because of its widespread use in the areas of medicine, nuclear energy, and industry. Malformations induced by radiation at the organogenesis stage, skeletal malformations, and the effects at the cellular level of embryos were examined in this research. Further, the mechanism of the protection effect of TMG against radiation-induced malformations was analyzed and observed experimentally. Thus, this study was done to provide fundamental data on the radioprotective agent TMG. It was clear that TMG exerted radioprotective effects against embryonic death and the rate of teratogenesis when administered before exposure. Such effects were also exerted against skeletal malformations and fetal body weight. In summary, radioprotective effects were observed at the whole-body level as well as at the cellular level.

Abnormalities, Radiation-Induced↗
PubMed2000

Dental changes and space gained as a result of early treatment of pseudo-Class III malocclusion.

This study was designed to investigate the dental changes and the space gained following early treatment of pseudo-Class III malocclusion, using a simple fixed appliance. Twenty-one consecutively treated patients who had a pseudo-Class III malocclusion comprised the treated group. Fifteen untreated control subjects were used as matched controls for the three-year follow-up after completion of treatment. Lateral cephalograms and study models were analysed for the treated, the control and the follow-up group. The arithmetic mean and standard deviation were calculated for each variable, and paired t-tests were performed to assess the effects of treatment on the treated group. The Mann-Whitney test was performed to evaluate the difference between the follow-up group and the control group. Anterior crossbites and mandibular displacements were eliminated after the treatment. On average, the space gained as a result of the treatment was 4.7 mm in the upper arch (p < 0.001 degree). Comparison of the space available as a result of early treatment with the space required for alignment of posterior segments in the upper arch of the untreated control group indicated that there was enough space for the eruption of the canines and premolars as a result of early treatment; whereas, lack of space was evident in the untreated controls. In conclusion, a pseudo-Class III malocclusion, proclination of the upper incisors and/or retroclination of the lower incisors contributed to the correction of anterior crossbite and the elimination of mandibular displacement. Proclination of the upper incisors, utilisation of leeway space, and arch-width increase provided the space required for eruption of the premolars and canines.

Bicuspid↗
PubMed2000

[Discussion on the engineering problems in oral implantology].

The engineering problems in oral implantology are discussed in this paper. The problems discussed include the comparison among implants of different shapes, the influence of lengths and diameters of implants on the biomechanics properties of interface, the influence of pitches and tooth angles of threaded implants on the biomechanics properties of interface, the influence of methods of surface treatment and surface topography of implants on the biomechanics properties of interface, the characteristics of implant denture design, the application of picture treatment technology and solid model manufacturing technology in implant denture reconstruction.

Biomechanical Phenomena↗
PubMed2000

Synergetic effect of dialyzer membrane and lipopolysaccharide on peripheral blood mononuclear cell cytokine production in uremic patients.

OBJECTIVE: To investigate the effect of lipopolysaccharide(LPS) and dialyzer membrane on cytokine gene expression and protein production in uremic patients on continuous ambulatory peritoneal dialysis (CAPD) and regular hemodialysis(HD). METHODS: Interleukin-1 beta (IL-1 beta) and interleukin-1 receptor antagonist (IL-1Ra) produced by cultured peripheral blood mononuclear cells (PBMC) after exposure to cuprammonium (Cup) membrane, polysulfone (PS) membranes or endotoxin were detected using enzyme-linked immunoabsorbent assay. mRNA expression was determined simultaneously by in situ hybridization. RESULTS: In the absence of endotoxin, a small amount of IL-1 beta and IL-1 Ra was produced by PBMC harvested from HD and CAPD patients after incubation with Cup or PS during subsequent 24-hour culture. For healthy controls, IL-1 beta was barely detectable just above the detection limit. Although no differences could be found in protein synthesis between Cup and PS, in situ hybridization showed that Cup induced markedly higher level mRNA coding for IL-1 beta and IL-1Ra. In contrast, when subsequently stimulated with endotoxin, PBMC incubated with Cup could produce significantly larger amount of IL-1 beta and IL-1Ra compared with either unstimulated cells or post-incubation PBMC with PS. LPS-stimulated PBMC in healthy subjects produced similar amount of IL-1 beta and markedly lower IL-1Ra as compared with uremic patients on HD and CAPD. CONCLUSIONS: Two steps are required in healthy control for IL-1 beta and IL-1Ra production: induction of mRNA transcription by membrane contact, followed by LPS-induced translation, while in uremic patients on HD or CAPD bioincompatibility-membrane and LPS have a synergetic effect on IL-1 beta and IL-1Ra production. There exists an unbalance between IL-1 beta and its specific inhibitor in maintenance dialysis patients.

Adult↗
PubMed2000

The relationship between Th1/Th2-type cells and disease activity in patients with systemic lupus erythematosus.

OBJECTIVE: To investigate the imbalance of Th1/Th2-type cytokines in patients with systemic lupus erythematosus (SLE) and its relation to disease activity. METHODS: Intracellular cytokines were determined by flow-cytometry following whole-blood culture. RESULTS: Patients with systemic lupus erythematosus disease activity index (SLEDAI) > 10 had statistically significantly fewer CD4+ or CD8+ T cells producing IFN-gamma than patients with SLEDAI = 0, SLEDAI 1-10 or healthy controls (P < 0.01, P < 0.01 or P < 0.05, respectively). Patients with SLEDAI > 10 also had decreased ratio of IFN-gamma/IL-4 positive CD4+ or CD8+ T cells, compared with patients with SLEDAI = 0, SLEDAI 1-10 or healthy controls (P < 0.05). The decreased Th1 or Tc1 cells and the ratios of IFN-gamma: IL-4 positive CD4+ T-cells were significantly correlated with disease activity (P < 0.05). CONCLUSION: SLE is characterized by an imbalance of Th1/Th2 and Tc1/Tc2 cytokines. The decreased Th1 or Tc1 cells and the Th1/Th2 ratio are related to disease activity.

Adult↗
PubMed2000

[The invasive ability of bladder cancer].

OBJECTIVE: To find a direct method for testing the invasive ability of bladder cancer. METHOD: The invasive ability of 49 specimens of primarily cultured bladder cancer, transfected BIU-87 cells with pcDNA3-E1AF and untransfected BIU-87 cells was evaluated by Matrigel invasion assay. RESULTS: Sixteen of the 49 specimens were found to penetrate the matrigel barrier, and the result of the Matrigel invasion was related to the grade of the tumor cells. The number of positive cells of transfected BIU-87 was remarkably larger than that of untransfected BIU-87. CONCLUSIONS: Matrigel invasion assay is a simple, direct and dependable method, and could be used clinically to test the invasive ability of bladder cancer.

Adenovirus E1A Proteins↗
PubMed2000

[Radial artery for coronary artery bypass grafting: operative techniques and early results].

OBJECTIVE: To review the experience coronary artery bypass grafting (CABG) with the radial artery (RA) performed from June 1997 to December 1999. METHODS: A total of 71 patients received CABG in whom the performance of the radial and ulnar arteries were checked preoperatively with the modified Allen's test. A curvilinear skin incision was made from 3 cm distal to the cubital fossa to 2 cm before the proximal crease at the wrist. The RA was mobilized together with its satellite veins and surrounding fat tissues. Small branches were divided between titanium clips. Direct touching on the RA trunk was totally avoided and use of diathermy was minimized. A 1% papaverine solution of heparinized Ringer's was applied intraluminally into the free RA graft before it was stored in the same solution for later use. Seventy-two RAs were harvested and 79 distal anastomoses were made mostly to the posterior descending branches and the circumflex marginal branches. All the proximal anastomoses were directed to the aorta. Calcium channel blockers were routinely used for a period of 6 months postoperatively. RESULTS: There was 1 death for an operative mortality of 1.4%. The death was not caused by failure of RA graft. There was no compartment syndrome or hand ischemia. No perioperative myocardial infarction was observed. CONCLUSIONS: It is easy and safe to use the RA for CABG by which good results can be achieved. A'no-touch' harvesting technique and use of calcium-channel blockers are essential to the functioning of this conduit.

Adult↗
PubMed2000

[A case control study on the distribution of apolipoprotein AI gene polymorphisms in the survivors of atherosclerosis cerebral infarction].

OBJECTIVE: To investigate the frequency of the restrict fragment length polimorphisms (RFLP) at 2 MspI sites in the 5' - end of apolipoprotein AI (ApoAI) gene and its potential interaction to atherosclerotic cerebral infarction (ACI) in Chinese Han population. METHOD: Polymerase chain reaction (PCR) technique was used in a sample of 199 cases with documented ACI and 204 healthy matched by age and sex individuals selected from Chinese Han nationality in Beijing. The studied loci include promoter region (-75 bp) and the intron - 1 (+83 bp). RESULTS: (1) Both ACI and control groups M1 + + and M1 + - were major frequent genotypes in Beijng area, M2 + + were major frequent genotypes in intron - 1; (2) M1 + - genotype appeared more common among patients than in controls (0.487 vs 0.368, P < 0.05, OR = 1.64); (3) Individuals with M1 + -/M2 + + haplotype were significantly increased in patients compared with controls (0.437 vs 0.314, P < 0.05, OR = 1.70). CONCLUSION: It is suggested that both M1 + - genotype and M1 + -/M2 + + haplotype of ApoAI gene might associate with ACI in our study.

Apolipoprotein A-I↗
PubMed2000

[The effect of injuries on Fn synthesized by FBs and its implication in wound timing].

cFn synthesized by FBs around the wound was detected by immunochemistry in vitro. Using the method of ELISA, The concentration of cFn in the culture media was observed. The concentration of cFn had no change within 30 minutes after injury, but started to increase after 1 hour of the injury and kept this trend within next five hours after injury. By static analysis, it can be obtained that the concentration of cFn in culture media is time-dependent after injury.

Cells, Cultured↗
PubMed2000

[The muscarinic receptor subtype study of the action on lowering IOP of cholinomimetic drugs].

PURPOSE: Clarify the relationship between lowering intraocular pressure (IOP) action of cholinomimetic drugs and muscarinic receptor subtypes. METHODS: Measuring rabbit IOP with gas driving ophthalmotonometer, measuring size of pupil with pupil rule and measuring contraction of rabbit iris by iris experiment in vitro. Figuring out pD2 of cholinomimetic drugs and pA2 of the antagonists of muscarinic receptor subtypes. RESULTS: The order of effect on lowering IOP and miosis of cholinomimetic drugs is Erycibele Alkaloid > Aceclidine > Pilocarpine and the order of effect on constracting iris is Erycibele Alkaloid > Pilocarpine > Aceclidine. The sequence of antagonistic effect of subtype antagonists is 4-DAMP(M3) > Pirenzepine(M1) > Gallamine(M2). CONCLUSION: Effect cholinomimetics on lowing IOP and miosis is primary mediated by M3 receptor, next by M1 receptor and has little relation with M2 receptor.

Animals↗